By RICHARD BERNSTEIN

basic question posed by students of the Holocaust has to do with the psychology of the ordinary perpetrators of the genocide against the Jews. How, some scholars have asked, did those who carried out the slaughter overcome the moral scruples it would be normal to feel when faced with the annihilation of an entire people, a far-flung people, moreover, that posed no threat to the German homeland.

That is the wrong question, Daniel Jonah Goldhagen argues in this masterly, powerfully argued book. ''Hitler's Willing Executioners'' is an attempt to demolish the standard views about Germans and the Holocaust by arguing that when it came to the Jews, average Germans had no moral scruples to overcome in the first place.

The perpetrators of the anti-Jewish slaughter, Mr. Goldhagen contends, did not kill Jews because of threats or some German propensity for obeying authority. They participated in the slaughter because they were steeped in a historical culture of anti-Semitism. They tortured and massacred Jews, starved them, toyed with them, punished them for their birth, and they did so voluntarily, even eagerly, with unsurpassable malice and cruelty.

''The German perpetrators,'' Mr. Goldhagen wrties, ''were assenting mass executioners, men and women who, true to their own eliminationist anti-Semitic beliefs, faithful to their cultural anti-Semitic credo, considered the slaughter to be just.''

Mr. Goldhagen, an assistant professor of government and social studies at Harvard, has not eliminated all possibility of disagreement with his thesis. He may underestimate the effects of pervasive state terror, the puniness of the individual living in the leviathan state. Other recent historical horrors -- Stalin's terror, the Cultural Revolution in China -- show that mass fealty can be whipped up by a totalitarian leader, operating in an atmosphere of state terror, without any particularly deep, preceding cultural hatred for the victim groups.

But if Mr. Goldhagen has not pre-empted all possible doubts over his conclusions, the copiousness of his evidence and the elegance of his logic sweep away the large mass of them. His book is one of those rare new works that merit the appellation landmark. The evidentiary and moral heart of ''Hitler's Willing Executioners'' comes in several chapters in which Mr. Goldhagen examines three of the institutions of the Final Solution: police brigades that were enlisted in the anti-Jewish measures, slave labor camps, and the death marches, especially those that came at the end of the war.

Others have studied some of these institutions, notably Christopher R. Browning, whose 1992 book, ''Ordinary Men,'' is a searing portrait of Police Battalion 101, also investigated by Mr. Goldhagen. In his footnotes, Mr. Goldhagen, while admiring Mr. Browning's work, argues that ''Ordinary Men'' is wrong to accept claims that the battalion members were reluctant to kill Jews.

Whether Mr. Goldhagen is right about this, his depiction of the institutions of killing is the broadest study of the perpetrators of the genocide yet done. It also represents a high attainment in scholarship, in historical writing and in moral perceptiveness. There are overpowering passages in them as Mr. Goldhagen confronts the facts and then goes deeply into their meaning. Central to his argument is the role of sheer cruelty, the sadism involved in the killing, the evident joy taken by men and women alike in turning the unspeakable suffering of the Jews into sport.

To take just one example, Mr. Goldhagen describes the ordinary life of the German police battalions in Poland. Their members, often family men, spent days shooting naked women and children in ditches and then returned in the evening to their wives (who sometimes came to see them at work), to theatrical events, social clubs, soccer matches. ''One should with renewed strength take measures against cruelty to animals,'' reads one circular, discovered in the archives by Mr. Goldhagen. This order to Police Regiment 25, Mr. Goldhagen continues, then ''discussed the problem of packing cows too tightly into cattle cars!''

''Orders not to cram Jews too tightly into cattle cars never came the way of the Germans in Poland who deported Jews to their deaths, typically by using kicks and blows to force as many Jews into the railway cars as was possible,'' Mr. Goldhagen writes. He then subjects the police battalions to intense scrutiny, finding them to be broadly representative of German society. Thirty-eight battalions were stationed in occupied Poland, of which at least 30, with about 15,000 ordinary Germans in them, were involved in the mass slaughter of the Jews.

What is the meaning of cruelty? Even when a society executes criminals, as Mr. Goldhagen notes, it does so in ''a quasi-clinical manner: swiftly, without torment, and with minimum pain.'' By contrast, Mr. Goldhagen says, ''the Germans' killing of the Jews was often wrathful, preceded and attended by cruelty, degradation, mockery, and Mephistophelean laughter. Why?'' Mr. Goldhagen's answer centers on the Germans' hatred for the Jews, a hatred so deep that it was akin to a kind of mysticism: ''In their eyes, der Jude is not merely a heinous capital criminal. He is a terrestrial demon.''

Mr. Goldhagen's morally unsparing analysis will no doubt provoke much debate and quite likely some protest. He is, after all, essentially saying that the crime of the Holocaust was the reflection of a special iniquity lying within the German culture and the German people. That seems almost too extreme a conclusion to be true. But Mr. Goldhagen reminds us that near the end of the war, the Germans were ordered by Himmler to stop the killing, but they continued anyway. The author asks his readers to imagine the Danes or the Italians openly informed by their leaders that their goal was ''to kill, root and branch, another people.'' The reaction, he says, would be ''as to the words of a madman.'' Just such a mad program was announced to Germans. ''They evinced not surprise, not incredulity, but comprehension,'' Mr. Goldhagen writes. ''The annihilation of the Jews made sense to them.''